It is known to fit the rear window opening of a truck cab with a sliding window assembly made up of a pair of stationary panes mounted outboard in a window opening to define a gap therebetween, and one or two sliding panes retained along their upper and lower edges in guide tracks for horizontal movement. Many different electrically powered window regulator mechanisms have been proposed to allow an occupant of the truck to open and close the sliding window by actuating a switch.
These prior art regulator mechanisms generally include a guide rail extending along the lower edge of the window assembly and one or more pane carrier blocks reciprocally movable along the guide rail. A reversible electrical motor drives a cable, slotted tape, or a rack-and-pinion mechanism to move the carrier block along the guide rail, and the carrier block engages an attachment secured to the sliding pane to pull it between the open and closed positions.
One drawback to the previously-known regulator mechanisms becomes apparent if there is a failure in the motor, electrical power supply, or other critical component of the drive system. In the event of such as a failure, it is important that the occupant of the truck be able to open and close the window manually. Heretofore, it has been impossible or inconvenient for the occupant to disengage the regulator mechanism from the sliding panes to permit such manual operation.
Another limitation of the prior art regulator mechanisms is that the carrier blocks make a rigid connection with the pane attachment on the sliding pane so that any movement of the pane perpendicular to the direction of sliding movement and any tipping of the pane is transferred directly to the carrier blocks, and vice versa. Accordingly, the rigid connection between the carrier blocks and the pane may tend to cause binding problems when the track in which the sliding pane travels is not perfectly flat and parallel with the guide track in which the carrier blocks slide.
U.S. Patent application Ser. No. 09/126,649, assigned to the assignee of the present patent application, discloses a window regulator in which a pane carrier engages a sliding pane by means of a male/female connection which restrains the sliding pane against tipping and binding within its guide track yet allows relative movement between the pane carrier and the sliding pane along an axis perpendicular to the pane. This type of connection allows the regulator to operate properly, without binding or jamming, when attached to a window assembly that is not perfectly flat along in the direction of sliding movement. It is also simplifies the assembly process, since the regulator does not have to be attached to the window assembly with a great deal of precision.